The invention concerns novel polynitrogen containing salts of polyboron oxyacids compounds. The invention also concerns their preparation and use. The use can additionally concern flame retardants compounds and compositions in which said polynitrogen containing boron compounds are employed and their preparations.
Certain useful boron compounds are known such as boric acid, orthoboric acid, metaboric acid, tetraboric acid, borax (Na2B4O7), kernite, calemonito, ammonium tetraborate (NH4HB4O7), ammonium tetraborate (NH4)2B4O7), zinc borate (Zn)2(B2O3)3 which is sold under the tradename xe2x80x9cFIREBRAKE ZBxe2x80x9d by U.S. Borax, Inc. These boron compounds must be used with other flame retardant compounds such as phosphorus compounds or halide compounds in order to produce a satisfactory flame retardant compound. Many U.S. Patent include boron acids and their derivities utilized with another flame retardant agent such as halogen containing compounds, nitrogen containing compounds, phosphorus containing compounds and sulfur containing compounds. It is well known in the Arts that the known salts of boron compounds alone are not a satisfactory flame retardant compound whereas the novel flame retardant polynitrogen containing salts of boron oxyacid compounds are good flame retardant compounds and may be used alone. The known basic salts of boron compounds form complex, large molecule compounds by the reaction of the boron atoms reacting with the oxygen atoms on other boron radicals. These complex salts of boron oxyacid do not beak down into acid compounds which produce char which protect the flammable material. This condensation process can be prevented by the process of this invention while producing novel flame retardant polynitrogen containing salts of boron oxyacids. These complex, large molecule salts of boron compounds such as ammonium borate (NH4HB4O7 are broken down into smaller molecules by the molecules reacting with water in the present of a strong bases such as ammonium hydroxide and at the same time the ammonia reacts with the smaller molecule of salt of boron compounds to form polyammonium salt of polyboron oxyacid. This reaction also prevents the reformation of large complex molecules when the compounds are dried. On page 637 of General Chemistry by Mebergall-Schmidt-Holtzclaw, 4th addition published by D.C. Heath and Company, Lexington, Mass., illustrates that the borate salts form large molecules in units of B4Oxe2x80x942, such as ammonium borate, This formation of large molecules interfere with the flame retardant properties of the known boron salts. These large complex molecules of the salts of boron compounds when heated in a flame does not break down into sufficient acidic radical which produce charring of the burning flammable material. This charring is necessary to stop the flame by forming a char over the burned area. The flame retardant polynitrogen containing boron oxyacid compounds of this invention when heated by a flame breaks down into acidic radicals which produce charring and also the nitrogen containing radical also has flame retardant properties.
In one aspect, the invention comprises polynitrogen containing salts of boron oxyacids.
Another aspect of the invention is a process to prepare polynitrogen containing salts of boron oxyacids comprising serially contacting
A) boron oxide, dried boric acid and/or salts of boron compounds; 25 to 100 parts by weight;
B) nitrogen containing salt forming compounds; 25 to 100 parts by weight;
C) water, free or attached to molecules; 10 to 100 parts by weight; under conditions sufficient to prepare a polynitrogen containing salt of boron oxyacid compound. These polynitrogen containing salts of boron oxyacid compounds are useful flame retardant compounds and surfactant.
The flame retardant use comprises contacting an otherwise more flammable organic material with the polynitrogen containing salts of boron oxyacids thereof under conditions sufficient to lower the combustibility of the otherwise more flammable organic material, for example, an otherwise more combustible plastics, polyurethanes and natural products. Thus, a further aspect of the invention is a flame retardant composition comprising an otherwise more flammable organic material incorporated therewith a flame retardant amount of a polynitrogen containing salt of boron oxyacid.
In general, the polynitrogen containing salt of boron oxyacids of this invention are produced utilizing boron oxide, dried boric acid and/or salts of boron oxyacids which are reacted with a strong basic compound in water such as concentrated aqueous ammonia. The large complex molecule salts of boron are broken down into smaller molecules by reacting water with one or more of the crosslinking oxygens which are then reacted with the strong basic compound to form a polynitrogen salt of boron oxyacids, such as polyammonium salt of boron oxyacids. The polynitrogen containing salts on the boron oxyacid molecules prevent the formation of large complex molecules. The ability of the polynitrogen containing salts of boron oxyacids of this invention to breakdown when heated into acidic radicals which produce a char on the flammable material along with a nitrogen containing flame retardant radical to stop the flames are improvements over the known salts of boron.
When one mol of boron oxide (B2O3) or dried boric acid are added to concentrated aqueous ammonia containing 2 or more mols of ammonia they react to produce a mixture of ammonium diborate (NH4)HB2O5, diammonium diborate [(NH2)2H2B2O5] and ammonium salt of boric acid (NH4BO3) but predominately diammonium diborate. When the mixture is dried two mols of ammonium salt of boric acid loss a mol of water and form more diammonium diborate.
When boric acid is added to an excess amount of concentrated aqueous ammonia they react to produce ammonium borate ( NH4BO3) then upon drying two moles of the ammonium borate react to form diammonium diborate.
The polynitrogen containing salt of polyboron oxyacid compounds of this invention can be represented by the general formula of
(y)n(M)eHvBxOz
wherein y is a nitrogen containing salt forming radical, n is a number 2-4, M is a metal radical, e is a number 0-2, v is a number 0-3, x is a number 1-2 and z is a number 5-7.
The fire retardant polyammonium polyborate of this invention has the general formula of
(NH4)nHvBxOz
wherein n is a number 2-4, v is a number 0-3, x is a number 2-4 and z is a number 3-7.
Basic salts of boron oxyacids such as monoammonium pentaborate tetrahydrate produced by U.S Borax, Inc. is broken into smaller molecules by adding it to a concentrated aqueous solution of ammonia thereby producing a polyammonium salt of a polyboron oxyacid. When zinc borate [(ZnO)2(B2O3)3trihydrate] produce by U.S. Borax, Inc, is added to an excess of concentrated aqueous ammonia the zinc borate is split into smaller molecules by water then the ammonia reacts with the molecules to produce ammonium zinc borate and polyammonium zinc borate which are good flame retardant compounds. When amino borates such as melamine borate produced by Chemie Linz is added to an excess of concentrated aqueous ammonia the melamine borate is split into smaller molecules by the addition of water then the ammonia react with these molecules. Other alkaline metal borates such as borax and alkaline earth metal borates such as calemanito will react with concentrated aqueous ammonia to produce smaller molecules of ammonium alkali metal borate, polyammonium alkali metal borate, ammonium alkaline earth metal borates or polyammonium alkaline earth metal borates.
Any suitable boron compound may be used in this invention. Suitable boron compound include, but not limited to, boron oxide, dried boric acid which was heated to remove water, boron oxyacids such as orthoboric acid, metaboric acid and tetraboric acid, metal borates, alkali metal borates, alkaline earth metal borates, ammonium borates, amine borates, polyamine borates, amino borates such as urea borates, melamine borates, etc., polyamide borates and mixtures thereof. Boron oxide is the preferred boron compound.
Any suitable nitrogen containing salt forming compound may be used in this invention. Suitable nitrogen containing compounds include, but not limited to, ammonium hydroxide, amino compounds, amines, polyamines, amides, polyamides, aminoplasts, ammonium carbonate, alkyl carbamates, sulfamic acids, ammonium sulfamate, thioureas, quaternary ammonium salts, alkylanolamines, nitriles, alkyl isocyanates, organic ammonium salts, etc., and mixtures thereof. Suitable amino compounds include, but not limited to, urea, alkyl urea, buiret, amino condensation compounds, ammonium polyaminocarbamate, melamine, melamine cyanurate, dicyandiamide, guanidine, cyanoguanidine, ammeline, aminoguanidine and mixtures thereof. Ammonium hydroxide is the preferred nitrogen containing compound.
The novel flame retardant polynitrogen containing salt of polyboron oxyacid of this invention is a very good flame retardant compound and insecticide when used alone but may also be use with other flame retardant compounds, fillers and carbonization auxiliaries in a flame retardant composition. Any suitable carbonization auxiliaries that in the presence of fire assist the formation of a carbonization foam and/or char, such as, additives that produce acidic components in the pyrolysis mixture, such as phosphorus acids, boric acids or sulfuric acids. These acidic components are compounds such, for example, acids or salts or their derivatives of sulfur, boron and phosphorus, such as, boron-phosphate, phosphates, and polyphosphates of ammonia, amines, polyamines, amino compounds, thiourea, and alkylamolamines, but boric acid and its salts and their derivatives, organic phosphorus compounds and their salts, halogenated organic phosphorus compounds, their salts and their derivatives may also be used for this purpose. The carbonization auxiliaries and other flame retardant agents may be used in quantities of 0 to 300 percent by weight of the polynitrogen containing salt of polyboron oxyacid. The nitrogen salts of phosphorus acids are the preferred carbonization compound such as the amino phosphates.
Any suitable filler may be used in this invention. The fillers that may be utilized in the flame retardant mixture are usually insoluble in the reaction mixture. They may be inorganic substances, such as, alkali metal silicates, alkaline earth metal silicates, metal silicates, silica, metals, metal oxides, carbonates, sulphates, phosphates and borates, glass beads or hollow beads. Hydrated aluminum oxide is the preferred inorganic filler. The fillers may be organic substances, such as amino compounds, such as, urea, melamine, dicyandiamide and other cyanuric derivatives or their formaldehyde resins, aminophosphates, amino salts of organic phosphates, phenolaldehyde resin powder, powdered coke, graphite compounds and mixtures thereof. The organic halide flame retardant compounds may also be used as fillers. Fillers may be used in the amount of 0 to 300 parts by weight based on the weight of the polynitrogen containing salt of boron oxyacid.
Any suitable organic material which is more flammable than the polynitrogen containing salt of boron oxyacid may be used in this invention. Any suitable plastic resin composition or mixtures thereof and any suitable natural organic material may be used in this invention and mixtures thereof. These materials may be in the form of a solid, cellular suspension, emulsion or solution. Suitable plastic resin include, but not limited to, vinyl dienes, vinyl-diene copolymers, polyesters, polyester resins, phenoplasts, aminoplasts, polyepoxy resins, polyurethanes, furans, polyamides, polycarbonates, homopolymers of such olefins as ethylene, propylene, and butylene; block copolymers, consisting of optional combination of these olefins; polymers of vinyl compounds such as vinyl chloride, acrylonitrile, methyl acrylates, vinly acetates and styrenes; copolymers of the foregoing olefins with vinyl monomers, copolymers and terpolymers of the foregoing olefins, with diene compounds; polyesters such as polyethlylene terephthalate, polyester resins; polyamides such as nylon; polycarbonates, polyoxymethylene, silicones, polyethers, thioplasts, polytetrafluoroethylene, polysufones, vinyldienes, poly(vinyl acetete), aliphatic allyl compounds, polyacrylonitrile, aliphatic dienes, polybutadiene, butadiene-acrylonitrile, butadiene-styrene copolymers, aromatic vinyl compounds, heterocyclic vinyl compounds, cyclic unsaturated compounds, polyurethanes, urethane-epoxy resins, polyimides, urethane silicates, cellulose nitrate rayon, regenerated cellulose film cellulose acetate, cellulose esters, cellulose ethers, cyanoethyl cellulose, chlorinated rubber and mixtures thereof.
Suitable natural products include, but not limited to, wood, cellulose, lignin-cellulose, paper, cotton, wool, linen, dammars, copols, other natural resins, rosins, lignin, natural rubber, natural proteins, e.g., soya bean protein, silk, glues, gelatin, etc.; modified cellulose and mixtures thereof. Natural organic and plastics may be mixed together.
The preferred method to produce the polynitrigen containing salt of polyboron oxyacids is to add the boron oxide, dried boric acid, boric acid or salts of boron oxyacids to an aqueous solution, emulsion or suspension of ammonia, amine, polyamine, amino compounds, etc. at ambient temperature and pressure. In some reactions it is necessary to cool the mixture or heat the mixture, When ammonia is used it is necessary to increase the pressure or cool the mixture. When amino compounds are used it is preferred to react the amino compounds with the boron oxyacid then add an excess amount of aqueous ammonia to react with the remaining boron oxyacid radicals thereby producing a polyammonium amino salt of boron oxyacid. The preferred method to produce polyammonium salt of polyboron oxyacid is to slowly add the boron oxide or boron oxyacid to an excess concentrated aqueous ammonia while agitating and keeping the mixture below the temperature that ammonia boil out of the water, the reaction is complete in 1 to 6 hours. The mixture is then dried and pulverized into a powder.
The powdered polynitrogen containing salt of polyboron oxyacids or polynitrogen salt of boron oxyacid may be added to the plastic when it is in the form of a liquid, emulsion, suspension or mixed in melted plastics. It may be added to the monomer components before producing the plastics. This flame retardant compound may also be applied to the exterior surface of the solid or cellular plastic or natural products. The powdered polynitrogen containing salt of boron oxyacids or polynitrogen salt of polyboron oxyacid may be used in an amount of 1%-100% by weight based on the weight of the more flammable organic material.
The more flammable organic material with the flame retardant polynitrogen containing salt of polyboron acids, polynitrogen containing metal salt of polyboron oxyacids and/or polynitrogen containing salt of boron oxyacid incorporated in the material were tested using a 2xe2x80x3 propane flame applied to the material for 1 minute, The flame did not spread and went out when the propane flame was removed. The flammable organic material tested burned without the flame retardant being present. On tested samples of these flame retarded materials using the oxygen index test the oxygen index was raised 10 to 30 percent.